I would submit they have not figured out how to make it profitable, lest we would not be in the situation that we're in.
Clearly there is a dissonance between the product your consumers want, your content, and the product you're willing to offer them: your content mixed with advertisement. That's an unfortunate situation.
Why does the advertisement make you money in the first place though ?
Someone out there with an actual product or service, want's to sell their product.
To increase sales, they pay you an amount of money that they think represents the amount of sale they will generate from the buyers that buy based on the advertisement run on your site. Whether it's through the proxy of some ad network or not.
If I am not willing to buy any products in the first place, I don't have to be factored into the amount the company is willing to pay to advertisers, as it will not increase their sales. If, based on just viewing the advertisement, I still am, that price is slightly inflated.
All what I am doing by blocking ads is bringing that price closer to it's actual value. Now, that's not in your interest as a content producer, but you don't have to be all moralistic about it and try to make me feel bad.
You might argue that that's incorrect, and after viewing enough advertisement I might be persuaded to buy a product that I would not have wanted to by before, but I am not willing to give you that power over my mind for mundane stuff like deodorants and beverages.